According to law-enforcement records, Giddings had been considered "an extremely dangerous" person, and instead of serving the minimum, he remained in custody for a decade.
But despite a thick file of 22 disciplinary infractions while behind bars, officials said, he was paroled in August.
After his release, officials said, police came across Giddings again.
About 1 p.m. on Aug. 27 in North Philadelphia, police said, Giddings was pulled over for a traffic violation in a car they later learned was stolen.
Giddings fled, taking police on a car chase through North Philadelphia, where he eventually bailed and ran. Police chased and got into a violent struggle that ended with two Highway Patrol officers rushed to the hospital with neck and back injuries.
Giddings got away.
Two days later, police issued a warrant for his arrest, noting that the suspect was known to spend time around 25th Street and Cecil B. Moore Avenue, 55th Street and Chew Avenue, Griscom Street near Arrott, and 66th Street near Malvern Avenue.
The warrant noted Giddings had "RIP MACK" tattooed on his left bicep, and "Theresa" on his right arm.
When Officer McDonald made a traffic stop yesterday about 1:45 p.m., police said, there was no indication he knew who Giddings was as the suspect bolted from the car and the officer pursued him on foot.
Rather than face more time in jail, police said, Giddings pulled a .45-caliber semiautomatic and shot McDonald. When the officer fell, he stepped over the body and fired several more shots before he ran.
"It was an execution," said Homicide Capt. James Clark. "He meant to kill him."
Minutes later, he tried to shoot his way to freedom again. That time, he was fatally struck when police returned fire.
Contact staff writer Barbara Boyer at 215-854-2641 or bboyer@phillynews.com.
